Is my Transmission Broken?

[Lee_Enfield]

Hello,

I have been driving my M3 a bit now that its on the road, and have a few questions. There are a few odd things that I occasionally notice when shifting.

It is a Manual with around 220000km (136000ish miles)

First, Sometimes while shifting into first or second, you think its in gear, you feel it pop into the de-tent, but its not. Happened a few times lately. I noticed it last year and chalked it up to a really sloppy shifter due to bad bushings. I threw in a new set, it feels great, but same issue.

Second one, Sometimes when shifting, seems any gear, you feel a slight "kick" in the shifter. Not a gear grinding noise at at all, almost like something hit something in the mechanism. Shift fine, but you feel and sometimes hear a knock. Once again its not a gear grinding noise, but rather a single bump.

I am Dreading a bad gearbox. My understanding is these are not serviceable, and a toast box is a new box.

Any input?

[PSUEng]

This may not help, generally my experience has been, the higher the revs, the easier the shifts. Change the fluid every 30k miles, and while bushings could be the culprit, i'm guessing lack of fluid changes may be the cause here? go change the fluid with proper spec oil see if that improve the situation. This ain't no S2000 gearbox--it's clunky and takes some input to operate...

[Lee_Enfield]

This may not help, generally my experience has been, the higher the revs, the easier the shifts. Change the fluid every 30k miles, and while bushings could be the culprit, i'm guessing lack of fluid changes may be the cause here? go change the fluid with proper spec oil see if that improve the situation. This ain't no S2000 gearbox--it's clunky and takes some input to operate...

I forgot to mention I did do the fluid last year, maybe 3000km ago? Used BMW fluid.

[Thoglan]

The double step into first and second gear is 'normal' for these. The synchro design on those gears makes them a bit of a pig to change through especially when cold and if you get the timing off. Some wear will be related to the issue. Don't let it grind, everytime it grinds you are making it worse. Don't let the clutch out if the gear doesn't fully engage. Take it out of gear, let the clutch up, blip the throttle, and select the gear again.

There are a few people that can service the gearboxes but it almost always makes more sense economically to just buy a used one.

[cobra]

My transmission used to do some pretty weird stuff back in the day. Double clicks... popping out of 2nd gear... overall clunkiness. I switched to Amsoil MTF transmission fluid and it's been much much better ever since. It's not a perfect smooth transmission by any means, but nothing I'd consider abnormal anymore.

[heinzboehmer]

Yep, both those things sound normal for these gearboxes. Some seem to do it more than others but it's been there to some degree on all the cars I've been in.

I've replaced every single part that's replaceable (shifter, bushings, detents, springs, clutch, flywheel, etc.) in an effort to try and improve the feel and, while the overall feel has gotten better, those two things your describe are still there.

[sapote]

First, Sometimes while shifting into first or second, you think its in gear, you feel it pop into the de-tent, but its not. Happened a few times lately. I noticed it last year and chalked it up to a really sloppy shifter due to bad bushings. I threw in a new set, it feels great, but same issue.

Second one, Sometimes when shifting, seems any gear, you feel a slight "kick" in the shifter. Not a gear grinding noise at at all, almost like something hit something in the mechanism. Shift fine, but you feel and sometimes hear a knock. Once again its not a gear grinding noise, but rather a single bump.

A worn or broken gear-position-detent pin/roller (the GPS attached to this) might cause this, so you might want to remove this detent and try again to see if it engages smoother. With the detent removed you might need to keep the shifter in place to avoid the gears pop out though, but of course this is a temporary for a test. The detent is mounted on the left near the rear of the tranny. It pushes again the main shift rod.

[bmwfnatic]

I am going to have to agree with heinzboehmer, my experiences are similar.

When I first got the car, the next day when I was leaving the neighborhood the same happened to me, somehow wasn't fully into 2nd gear and ground the gears.
Having driven manual all my life this shocked me, it happened a few more times since then, but only like right after driving away in the morning, leaving the neighborhood at ~15 MPH.

I think my muscle memory somehow adapted to the 'longer' and 'double-notchy' throw into 2nd gear, because thinking about it now, the issue hasn't come back for at least the past 2 years.
I have changed nothing with regard to attempt to fix it, so it kinda fixed itself I suppose.

So I think I am going to call this one normal as well, do note that it never happened to me at significant speed / revs, if it does, then perhaps your gearbox is broken.

Hope that helps.

[Cubieman]

I have an issue going into 3rd sometimes and it sounds similar to what you have described as the "kick" possibly.

I normally don't ever launch the vehicle or slam shift it etc. but the few times I have done that I have had a 3rd gear issue almost each time.

When I am really on it (semi-redline shifts) and going from 2nd>3rd gear sometimes while entering 3rd it feels as though something is "blocking" my ability to engage 3rd. I will try to slam it into 3rd, and if I feel this "blocking" sensation and continue to push through and attempt my shift the gears almost always grind which is terrible at ~8k.

Maybe part of that was me nervous during a drag race but after that "blocked 3rd gear" deal happened 5 different times on my 2/3 shift I'm sure I've got a synchro issue or maybe linkage issue.

During regular street driving or even faster driving all is well, there is only sometimes a slight "snick" during a 2/3 shift, feels like a linkage issue if anything there.


The car basically blocking me from 3rd when drag racing told me not to ever do that again, made me feel bad to do that to the E46 M3.

[sapote]

Maybe part of that was me nervous during a drag race but after that "blocked 3rd gear" deal happened 5 different times on my 2/3 shift I'm sure I've got a synchro issue or maybe linkage issue.

So it was not much of a race with the 3rd gear blocked

This sounds like the rpm was too high and not synced to the output gear, and so the synchro was blocking the gears from engaging which is normal. If it was
at 8000 rpm with 2nd, then 3rd only can engage if rpm drops lower.

[Jimbo's M]

This sounds like the rpm was too high and not synced to the output gear, and so the synchro was blocking the gears from engaging which is normal. If it was
at 8000 rpm with 2nd, then 3rd only can engage if rpm drops lower.

Didn't realize that was normal. Thought it was my M being my M. That said, it's quite frustrating trying to hit third at 8000 rpm and all you feel is a wall. Once I get below ~6.5/7, it'll go in. I think I'll still keep'er anyway.

[Cubieman]

Didn't realize that was normal. Thought it was my M being my M. That said, it's quite frustrating trying to hit third at 8000 rpm and all you feel is a wall. Once I get below ~6.5/7, it'll go in. I think I'll still keep'er anyway.

Exactly, that is a better description, it does feel like you are hitting a wall. I want to be competitive with my buddies E60 M5 but I always have that issue.

I stopped that a while ago though, not the car to drag race in.

[Lee_Enfield]

Well that's good to hear at least. Thanks for the input.

[sapote]

Didn't realize that was normal. Thought it was my M being my M. That said, it's quite frustrating trying to hit third at 8000 rpm and all you feel is a wall. Once I get below ~6.5/7, it'll go in. I think I'll still keep'er anyway.

When the clutch pedal was pushed -- clutch disengaged -- the clutch disk was fast like a spinning top and its inertial is very high and took some seconds to slow down by itself, or shorter time by slowed down with the synchro (driver pushing the shifter to engage the synchro), or by double clutch: because the engine slows down faster than the clutch disk, and so by engaged the clutch (in neutral) will let the slowed down engine to pull the faster spinning clutch disk down to match with the 3rd gear, then disengage the clutch and shift into 3rd (this helps shifting in to 3rd quicker than just pressing the synchro to do the job). To do the whole double clutch fast, you don't need to completely let go the clutch pedal all the way up, but just let it up 1" or so (where the clutch start biting point) and this should be enough for the engine to slow down the clutch disk), then declutch and shift into next gear.

[sapote]

Clutch in act on this 1973 CSL (predecessor to the M3). I wonder what is the red line on this vintage 2-valve single camshaft engine (I'm not sure the CSL has dual cams or single but my 1973 3.0CSi only single). Those door plexiglass were bent like a bow at high speed -- couldn't they stiffen up for less bend to have better aerodynamic drag?

https://www.youtube.com/watch?v=hIn3Qk5FxJc